The field of the present invention is hypodermic syringes with safety systems for the avoidance of sharps injuries.
For some time the art has recognized the desirability of protecting personnel from accidental sharps injuries, or needle sticks, and against contact with fluid that leaks, drips or is sprayed from a syringe after the syringe is used to deliver an injection. Sometimes, after a syringe is used to inject fluid into a patient, some fluid remains in the syringe, particularly at the tip of the needle. This fluid may include the fluid injected into the patient from the syringe and/or body fluids from the patient such as blood. Any fluid remaining in the syringe after use of the syringe may leave the syringe, such as by leaking, spraying or dripping from the syringe and may contact persons or objects in the area. Syringes with retractable needles may be especially prone to this loss of fluid when the needle quickly retracts into the barrel of the syringe after injection.
More recently, concerns have been expressed about the possibility of transmitting serious or potentially fatal infections as a result of sharps accidents. Most recently, legislation requiring the use of safe needle technology is pending in a number of states and before the Occupation Safety and Health Administration. Safe, conveniently used and inexpensive systems are needed which reduce the amount of manual manipulation required to make the needle safe against sharps injuries and fluid dispersal.
The present invention is directed to apparatus and methods of operation for hypodermic syringe systems with retractable needles. The syringe includes a barrel and a plunger assembly slidably extending into the barrel with features and steps permitting further manipulation of the plunger following injection to retract a luer hub assembly and needle into the barrel.
In a first separate aspect of the present invention, the plunger assembly includes a hollow outer plunger assembly, a hollow inner plunger assembly and a resilient tension element extending between the two assemblies which is just substantially relaxed with the outer and inner plunger assemblies telescoped together. A releasable engagement between the outer and inner plunger assemblies is able to retain the assemblies telescoped to an extended position. Thus, a collapsible plunger is provided.
In a second separate aspect of the present invention, the first separate aspect may be further contemplated to include a socket on the outer plunger assembly and a resiliently mounted pin on the inner plunger assembly which engage with the plunger assemblies telescoped to an extended position. The barrel of the syringe may include a release element to engage the releasable engagement through manipulation of the plunger. Such manipulation may include extra force or torque on the plunger thumb button. Avoidance of required manipulation with the other hand or adjacent the needle can be avoided.
In a third separate aspect of the present invention, the first separate aspect is further contemplated to include indexing between the inner and outer plunger assemblies, a stop between the barrel at the plunger opening and the inner plunger assembly at its locking end and selective indexing between the overall plunger assembly and the barrel. Such constraints on the plunger assemblies enables operation of the system with minimal operator manipulation.
In a fourth separate aspect of the present invention, the plunger assembly includes a plunger and a cap at one end of the plunger. The cap has a cylindrical wall with a helical cam surface and a track extending longitudinally of the plunder assembly. The plunger includes a resiliently mounted lock that retains the cap and the plunger from rotating relative to one another. The resiliently mounted lock includes a disengagement ramp. The barrel includes an internal rail which is able to interfere with the resiliently mounted lock at the disengagement ramp to displace the lock from the track upon near full insertion of the plunger in the barrel. This displacement is able to fix the cap from rotating relative to the barrel and release the plunger to rotate relative to the cap. As such, the helical cam surface is able to interact with a follower pin on the plunger to rotate the plunger relative to the barrel while the cap remains from rotating relative to the barrel. In this way, rotation may be selectively employed to actuate the syringe retraction mechanism and otherwise the plunger remains indexed relative to the barrel during charging and injecting operations.
In a fifth separate aspect of the present invention, the plunger includes a probe extending from the seal end of the plunger. A seal stop is positioned about the probe and is held thereto by an axially releasable engagement between the probe and the stop. An annular seal is positioned between the plunger at the seal end and the seal stop. The seal is found to be in sealed engagement with the internal sidewall of the barrel with the seal stop in mated engagement with the plunger and in disengagement with the internal sidewall when the seal stop is disengaged from the plunger. The ability to reduce seal friction between the plunger and the barrel for needle retraction can thus be achieved.
In a sixth separate aspect of the present invention, the plunger assembly includes a probe at the seal end with a retainer lug on the probe. A luer hub assembly is positioned in the barrel with a body having a needle end, an engagement end, a means to retain a needle and a retainer surface which faces the body near the engagement end and is engagable with the retainer lug through rotation of the plunger. The plunger may thus be coupled with the entire luer hub assembly for further manipulation. The retainer surface and the retainer lug may be axially displaced from one another with the plunger assembly fully extended into the barrel even though the retainer lug is aligned in engagement with the retainer surface. The spacing is able to allow for a short retraction of the plunger prior to drawing on the luer hub assembly. This retraction is capable of being employed to void an associated needle of fluid.
In a seventh separate aspect of the present invention, the plunger assembly includes a probe extending axially from the seal end of the plunger. A seal stop is positioned about the probe. An axially releasable engagement enables the seal stop to be retained in mated relationship with the seal end of the plunger as well as axially released therefrom. The seal stop provides a vehicle for accomplishing functions advantageous for luer hub and needle retraction.
In an eighth separate aspect of the present invention, the seventh separate aspect is contemplated to further include a portion inwardly tapered on the internal sidewall of the barrel to cooperate with a seal about the luer hub assembly. Extraction of the luer hub assembly through the barrel can operate through the taper to gradually release the seal about the body of the luer hub assembly, reducing initial acceleration imposed on a retracting needle. Reduced acceleration can limit the amount of liquid separated from the needle during retraction.
In a ninth separate aspect of the present invention, a seal stop is associated with the seal end of the plunger assembly. The seal stop includes an inwardly facing cam surface facing a luer hub assembly which includes a latch pin engagable with an internal stop and having a cam follower engagable with the inwardly facing cam surface. The releasable seal stop is thus able to actuate the latch pin to release the luer hub assembly within the barrel from the internal stop.
In a tenth separate aspect of the present invention, the ninth separate aspect is contemplated to further include mutually engaging surfaces between the seal stop and the luer hub assembly able to draw the seal stop and the luer hub assembly toward one another to actuate the resiliently mounted latch pin. In this way, the seal stop releasably engaged with the seal end of the plunger can be released to become engaged with the luer hub assembly for release of the luer hub assembly from the barrel.
In an eleventh separate aspect of the present invention, a hypodermic syringe retraction method includes extending the plunger assembly and a resilient tension element within the barrel of the syringe where the plunger assembly includes an outer plunger and an inner plunger telescoped together. The outer plunger is drawn outwardly from the barrel to engage an engagement between the outer and inner plungers. The engagement between the outer and inner plungers is later released.
In a twelfth separate aspect of the present invention, the eleventh separate aspect of the present invention is further contemplated to include engaging the luer hub assembly with the plunger assembly by rotating a retainer log of the plunger assembly into spaced engagement with a retainer surface on the luer hub assembly.
In a thirteenth separate aspect of the present invention, the eleventh and twelfth separate aspects of the present invention are further contemplated to include axial pushing of a plunger cap and translating the actual push to rotation of the plunger assembly.
In a fourteenth separate aspect of the present invention, a seal stop releasably engaged on the seal end of the plunger is released to radially retract an annular seal held between the seal end of the plunger and the seal stop. The seal stop is also engaged with a luer hub assembly and the luer hub assembly is released from the barrel. With the annular seal retracted and the luer hub released, extraction of the luer hub from the end of the barrel is possible.
In a fifteenth separate aspect of the present invention, a seal stop is released from the seal end of the plunger which allows for radial retraction of a seal associated therewith. The seal stop is engaged with a luer hub assembly and drawn thereto through rotation of the seal stop. The drawing of the seal stop toward the luer hub assembly releases a latch pin engaged with the interior of the barrel. The transfer of engagement of the seal stop from the plunger assembly to the luer hub assembly thus effects multiple changes resulting in the retractability of the luer hub assembly through the barrel.
In a sixteenth separate aspect of the present invention, any of the foregoing separate aspects are contemplated to be employed in combination to greater advantage.
Accordingly, it is an object of the present invention to provide an improved method and apparatus for a needle retracting hypodermic syringe. Other and further objects and advantages will appear hereinafter.